The original grant, of which this is a continuation, began in 1970 and was entitled "Brain Stem Sensory Connections". The initial studies in animals suggested that studies of microsurgical anatomy in man would be rewarding and upon renewal of this grant in 1973 and 1976, progressively greater parts of it were related to microsurgical anatomy. Subsequent studies have led to significant new anatomic findings and publications related to the microsurgical anatomy of multiple intracranial structures. This studies helped to meet the need for detailed anatomic studies created by the rapid growth of microneurosurgery (clinical neurosurgery done using 3 to 40X magnification). In a recent study of surgical services in the United States, by the American College of Surgeons and the American Surgical Association, the application of micro-operative techniques to the treatment of intracranial tumors and vascular disease was ranked among the first order research advances in surgery during the last 25 years. Multiple studies of the sella turcica, cranial base, major intracranial arteries and the cranial nerves have been completed. During the proposed project period many studies in progress will be completed, selected prior studies will be expanded and our studies will be extended to multiple areas not previously examined using micro-operative techniques.